Urinary tract infection (UTI)

Urinary Tract Infection (UTI) refers to microbial infection affecting any part of the urinary system including the urethra, bladder, ureters, or kidneys. UTIs are among the most common bacterial infections encountered in clinical practice worldwide and occur across all age groups.

UTIs are broadly classified into:

• Lower UTI — involving the bladder (cystitis) and urethra

• Upper UTI — involving the kidneys (acute pyelonephritis)

UTIs may also be categorized as:

• Uncomplicated UTI: Occurs in otherwise healthy, non-pregnant women with structurally and functionally normal urinary tracts

• Complicated UTI: Occurs in men, pregnant women, children, elderly patients, or individuals with structural abnormalities, catheters, obstruction, immunosuppression, or comorbid disease

Important clinical notes

• Differentiation between upper and lower UTI in young children is often unreliable based solely on clinical findings.

• Upper UTI represents a potentially serious systemic infection requiring prolonged therapy and sometimes hospitalization or intravenous antibiotics.

• Untreated UTI may lead to renal damage, sepsis, or recurrent infection.

Etiology and Pathophysiology

Most UTIs occur through ascending bacterial infection from peri-urethral flora into the bladder and kidneys.

Common causative organisms:

Predisposing mechanisms include:

• Short female urethra

• Urinary stasis

• Vesicoureteral reflux

• Catheterization

• Impaired host immunity

Risk Factors

General Risk Factors

• Female sex

• Sexual activity

• Poor perineal hygiene

• Previous UTI history

• Diabetes mellitus

• Immunosuppression

• Dehydration

Structural and Functional Factors

• Urinary obstruction (stones, tumors)

• Benign prostatic enlargement

• Neurogenic bladder

• Indwelling urinary catheter

• Congenital urinary abnormalities

Special Populations

• Pregnancy

• Elderly patients

• Children

• Hospitalized patients

Signs and Symptoms

Lower UTI (Cystitis)

• Dysuria

• Urinary frequency

• Urgency

• Suprapubic pain

• Cloudy or foul-smelling urine

• Hematuria

• Burning sensation during urination

Upper UTI (Acute Pyelonephritis)

• Fever ≥38°C

• Flank pain or costovertebral angle tenderness

• Chills and rigors

• Nausea and vomiting

• Malaise

• Systemic toxicity

Atypical Presentations

• Elderly: confusion, delirium, falls

• Children: fever, irritability, poor feeding

• Pregnant women: may be asymptomatic

Diagnostic Criteria

Clinical suspicion supported by:

• Flank pain or tenderness

• Temperature ≥38°C

• Tachycardia or tachypnoea

• Hypotension (severe infection)

• Vomiting

• Altered mental status or confusion

Diagnosis should ideally be confirmed by laboratory testing.

Investigations

Laboratory Tests

• Urine dipstick

  • Leukocyte esterase

  • Nitrites

• Urine microscopy

  • Pyuria

  • Bacteriuria

• Urine culture and sensitivity

  • Gold standard diagnosis

  • Guides antibiotic selection

Blood Tests (Complicated Cases)

• Full blood count

• Renal function tests

• Blood cultures (suspected sepsis)

Imaging

• Ultrasound (Kidney–Ureter–Bladder)

  • Detect obstruction

  • Stones

  • Abscess

  • Structural abnormalities

CT scan may be required in severe or non-responsive infections.

Management

Management depends on infection severity, patient category, and complication risk.

Pharmacological Management

1. Acute Pyelonephritis

• Ciprofloxacin 500 mg PO every 12 hours for 7 days

Severe cases may require:

• Intravenous antibiotics

• Hospital admission

• Fluid resuscitation

2. Uncomplicated Cystitis (Adults)

• Ciprofloxacin 500 mg PO single dose

(Local antimicrobial resistance patterns should guide therapy where available.)

3. Complicated Cystitis (Adults)

• Ciprofloxacin 500 mg PO every 12 hours for 7 days

4. Pregnancy and Adolescents

• Amoxicillin/Clavulanic acid 500/125 mg PO every 12 hours for 7 days

Important considerations

• Avoid potentially teratogenic antibiotics in pregnancy.

• Always perform urine culture in pregnant patients.

• Test of cure recommended after treatment.

Non-Pharmacological Management

• Ensure adequate oral hydration

• Encourage frequent bladder emptying

• Maintain genital hygiene

• Avoid unnecessary catheterization

• Manage underlying causes (stones, obstruction)

• Pain control where necessary

Complications

• Recurrent UTI

• Renal abscess

• Chronic kidney disease

• Urosepsis

• Preterm labor (pregnancy)

• Renal scarring in children

Prevention

Individual Prevention

• Adequate fluid intake

• Urinate after sexual intercourse

• Proper wiping technique (front to back)

• Avoid prolonged urine retention

• Avoid excessive use of irritant hygiene products

Medical Prevention

• Control diabetes mellitus

• Early treatment of urinary obstruction

• Rational catheter use

• Prophylactic antibiotics in recurrent UTI (selected cases)

Patient Education

Patients should be advised to:

• Complete prescribed antibiotics fully

• Seek medical care if fever or flank pain develops

• Return if symptoms persist beyond 48–72 hours

• Avoid self-medication without urine testing

• Increase water intake during illness

Special Clinical Considerations

• Men with UTI → Always considered complicated

• Children → Require evaluation for structural abnormalities

• Recurrent UTI → Investigate anatomical or metabolic causes

• Catheter-associated UTI → Remove or replace catheter when possible